Water mist protection for forced ventilation interstitial spaces

ABSTRACT

Water mist fire protection systems and methods for the protection of data centers having a raised floor defining an interstitial space beneath the floor. The systems and methods include the location of a plurality of automatic water mist nozzles above and/or beneath the floor to generate a water mist for effectively addressing a fire in the presence of a flow of forced air ventilation through the interstitial space. The systems and methods of water mist fire protection include the interconnection of the automatic water mist nozzles to a water supply to provide for dry pipe or preaction systems and methods. Water mist fire protection of data centers using fire propagating cable is also provided.

PRIORITY DATA & INCORPORATION BY REFERENCE

This application is an international application of U.S. ProvisionalApplication No. 62/116,400, “Water Mist Protection for ForcedVentilation Interstitial Spaces,” filed on Feb. 14, 2015, which isincorporated by reference in its entirety.

TECHNICAL FIELD

This invention relates to fire protection systems and devices, and moreparticularly fire protection systems using automatic water mist nozzlesfor the protection of occupancies having interstitial spaces such as,for example, data centers.

BACKGROUND

Generally, a data center consists of an equipment room, utilities, andsupport infrastructure including for example, air cooling or handlingequipment and associated electrical and data cable. Industry acceptedrecommendations for the protection of data centers are provided in FMGlobal publication “Property Loss Prevention Data Sheet 5-32: DataCenters and Related Facilities” (Jul. 2012). The loss preventionrecommendations include protection recommendations for data centersusing water mist systems. More specifically, Data Sheet 5-32 providesdata center protection recommendations using an automatic water mistsystem FM Approved for protection of light hazard occupancies. Accordingto the FM recommendations, use of the water mist systems is subject tocertain restrictions or limitations including: (i) the water mist systemmust be a wet system, i.e., a system in which the automatic nozzles areattached to a piping system containing water and connected to a supplyso that water discharges immediately from nozzle operated by the heatfrom a fire; (ii) the data center to be protected must usenon-fire-propagating cables in its cable trays; and (iii) theventilation or air handling systems of the data center are to beinterlocked with the water mist system to shut down upon actuation ofthe water mist fire protection system.

For data center operations it is desirable to run its ventilationsystems independent of or without the restrictions of fire protection.Data center equipment rooms can be very large having square footageequal to one or more football fields. For such data centers, shuttingdown the ventilation system upon fire protection system operation can bean impediment to the data center operations particularly where anyindication of a fire is limited to a small area. Accordingly, it wouldbe desirable to have water mist fire protection systems for data centersin which the ventilation or cooling systems can provide for continuouscooling during fire protection operation. Additionally, it would bedesirable to have water mist fire protection for propagating andnon-propagating cable to provide additional flexibility in the datacenter construction and operation. Moreover, it would be desirable tohave water mist fire protection for a data center that can be configuredas a dry pipe or preaction system to keep water out of the system pipingin an unactuated state of the water mist system.

Criteria for FM Approval of water mist systems is provided in FMApprovals LLC publication “Approval Standard for Water Mist Systems:Class Number 5560” (Nov. 2012). In October 2014, FM Approvals made aconference paper presentation at the International Water MistAssociation (IWMA) Conference in Istanbul, Turkey entitled “PlannedUpdates to FM Approval Standard Class 5560, Water Mist Systems, for 2015Revision.” In the presentation, it was noted that the Class 5560Approval Standard does not evaluate the aforementioned Data Sheet 5-32restrictions. Accordingly, FM Approval set forth in its presentation theobjectives for evaluating water mist systems in data center protection:i) to evaluate specific fire load, e.g., cables for data processingequipment room; (ii) to evaluate forced ventilation; and (iii) toevaluate water delivery time delay including interlocked systems. TheIWMA presentation outlined fire test protocols and criteria for theprotection of data centers for above and below a raised floor withoutthe recommendation restrictions. A copy of the FM Approval conferencepaper is available at<http://iwma.net/fileadmin/user_upload/IWMC_2014/FM_Carpenter_Jon_IWMC_2014.pdf.

Accordingly in 2014, work was ongoing to enable fire testing of waterMist systems. for data centers without the FM recommendationrestrictions. However, the 2014 conference paper does not identifyspecific nozzles for use in the proposed fire testing, it does notidentify specific nozzle spacing or operational parameters, nor does thepaper outline the manner in which nozzles can be identified for use theproposed fire test or in ata actual data center environment without thesystem restrictions. At that time, there remained a need for a systemsolution which identified nozzles and their installation parameters toovercome the system restrictions of Data Sheet 5-32.

SUMMARY OF THE INVENTION

Preferred embodiments of water mist fire protection system and methodsare provided which overcome industry accepted restrictions on water mistsystems in the protection of data centers. Therefore, preferredembodiments of a water mist system for fire protection of data centerscan generate a water mist to effectively address a fire in the presenceof a forced ventilation; (ii) provide protection using fire propagatingcable; and/or (iii) provide effective water mist fire protectionfollowing a water delivery delay time. Thus in a preferred aspect,embodiments of a water mist fire protection system and its operationprovide fire protection for a data center with or during continuous orsimultaneous operation of the ventilation system of the data center. Thepreferred systems and methods include locating and interconnectingautomatic water mist nozzles either above or beneath a raised floor withoperation of the ventilation system is maintained on during the watermist generation. Moreover, the preferred water mist fire protectionsystems and methods provides for fire protection of propagating andnon-propagating cable. Preferred embodiments of the system can beconfigured for operation as either a dry pipe or preaction system inwhich interconnecting pipes of the system are maintained dry in anunactuated state of the system. Alternatively, embodiments of the systemcan be configured as a wet pipe system with protection for propagatingcables and/or in the presence of forced ventilation.

A preferred method is also provided for identifying water mist nozzlesfor use in a system that overcomes the FM recommendation restrictionsand that can satisfy recently developed fire test protocols by FMApproval. The preferred method employs a water mist distribution testand defines preferred criteria for water mist weight rate distribution.The preferred method identifies water mist nozzles generating apreferred water distribution rate in a preferred test set-up thatincludes a test deck and a test floor spaced from the test deck at aclearance distance of three feet (3 ft.) (0.9 m). A first test cabletray is mounted between the test deck and floor, a second test cabletray mounted between the test deck and floor with two nozzles locatedover the first cable tray and beneath the test floor to define adiffuser-to-floor clearance distance. Each of the two nozzles is spacedfrom a wall extending between the test floor and deck. A plurality ofcollection pans are located on the test deck and centered between thetwo nozzles. The plurality of collection pans including au array ofeight pans of four rows and two columns centered about and within onefoot of a midline between the two nozzles. The water distribution ratedecreases from the first row to the fourth row with the decrease fromfirst row to the second row is no more than 60% and the decrease fromthe second row to either the third row or the fourth row ranges from5-40%.

In addition to the identification of preferred nozzles for use in thesystems and methods of water mist fire protection, the preferred systemsand methods include preferred nozzle orientations, spacing and relativelocations with respect to the raised floor, cable tray and/or grate ofthe data center. Accordingly, preferred embodiment of the systems andmethods provide an above-the-floor configuration, a below-the-floorconfiguration; and/or a local application configuration to providelocalized water mist fire protection to the one or more cable trays. Thepreferred systems and methods include nozzles located above and belowthe raised floor in an upright orientation and alternatively in apendent orientation with a preferred nozzle to nozzle spacing and/orhydraulic design. Another preferred method of water mist fire protectionfor data centers includes obtaining a plurality of automatic mistnozzles; and distributing the plurality of nozzles for installation atleast one of above or below the raised floor to address a fire with amist in the presence of the continuous flow of air; protect firepropagating cable or provide for one of dry pipe or preaction fireprotection.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate exemplary embodiments of theinvention and, together with the general description given above and thedetailed description given below, serve to explain the features of theexemplary embodiments of the invention.

FIG. 1A is an schematic illustration of a preferred embodiment of aWater mist fire protection system in an exemplary data center;

FIGS. 1B and 1C are elevation and plan views of the interstitial spaceand system of FIG. 1A;

FIG. 1D is a plan view of the system of FIG. 1A for an alternatearrangement of the interstitial space of the data center;

FIG. 1E are plan and elevation views of another embodiment of the systemof FIG. 1A;

FIGS. 1F-1G are elevation and plan views of another embodiment of a thesystem of FIG. 1A;

FIGS. 2A-2B are elevation and cross-sectional views of a preferredautomatic nozzle for use in the system of FIG. 1A;

FIG. 2C is a preferred diffuser for use in the automatic nozzle of FIGS.2A-2B;

FIGS. 3A-3B are elevation and cross-sectional views of a preferredautomatic nozzle for use in the system of FIG. 1A;

FIG. 3C is a preferred diffuser for use in the automatic nozzle of FIGS.3A-3B;

FIGS. 4A-4B is a preferred test set-up for distribution testing of watermist nozzles.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Shown in FIGS. 1A-1C are various views of a preferred embodiment of awater mist fire protection system 100 for protection of a data center10. The exemplary data center 10 can be defined by a deck 12, a raisedfloor 14 disposed above the deck 12 defining an interstitial space IS inbetween. For the preferred fire protections systems 100 describedherein, the raised floor 14 is preferably disposed above the deck 12 ata distance or height H1 of no more than a maximum distance of 3.28 ft.(1.0 m) above the deck 12. The data center 10 includes a ceiling andmore preferably a suspended ceiling 16 disposed above the raised floor14. For preferred embodiments of fire protection systems 100 describedherein, the ceiling 16. is preferably located at a distance or height H2of no more than a maximum distance of 16.4 ft. (5.0 m) above the raisedfloor 14.

The representative data center 10 is configured for housing or storingone or more server cabinets 5 along with associated supporting equipmentsuch as for example, cables, cable trays and cooling equipment. Forexample, one or more above-the-floor elongate cable, trays 15 (15 a, 15b) can be disposed beneath the ceiling 16 with the tops of the trays ata distance or clearance of no less than a preferred minimum 5.74 ft.(1.75 m) below the ceiling; and one or more below-the-floor elongatecable trays 17 can be disposed in the interstitial space IS between thefloor 14 and the deck 12 with the below-the-floor cable tray(s) locatedbeneath the floor at preferred distance or clearance of no less than of12 in. (30.6 cm) from the floor 14. The cable trays 15, 17 may bealternatively respectively located closer to the ceiling and floorprovided the fire protection system 100 can effectively address a firein a manner as described herein. The cable trays 15, 17 can carryfire-propagating and non-fire propagating cable for use in the datacenter 10. Unlike fire protection systems for data centers constructedunder existing industry accepted standards or recommendations, thepreferred embodiments of the fire protection system 100 can provide foreffective fire protection of either type of cable.

The data center 10 can also include a ventilation system 18 along withassociated equipment for providing cool air CA in the interstitial spaceS between the floor 14 and deck 12 and throughout the data center 10 forcooling the equipment stored therein. Cool air CA can be delivered intothe storage space of the data center 10 by upward flow through one ormore openings in the raised floor 14, for example, through one or morefloor grates 20 or grated regions installed throughout and/or about theraised floor 14. Heated air HA coming off of the aisles between thecabinets 5 can be returned or pulled back to the ventilation system 18.

A preferred embodiment of the system 100 includes a plurality ofautomatic water mist nozzles 102 for receipt of water delivered at adesired working pressure in which each nozzle preferably has a diffuser102 a for generating and dispersing a water mist to effectively addressa fire. A network of pipes 104 interconnect the plurality of nozzles 102to one another and an appropriate water source or supply FL to provideeach nozzle with the water at its working pressure. The piping can beconstructed from any material suitable for water mist systems includingfor example, stainless steel piping, CPVC piping and/or internallygalvanized piping. The water supply or source FL can be for example, aconnection off of municipal water supply system, and more preferably iscapable of supplying 60 minutes of water to the most remote, moreparticularly most hydraulically remote eighteen nozzles 102 in thesystem 100.

As a water mist fire protection system, the system 100 protects the datacenter and equipment stored therein by addressing a fire and morepreferably controlling Class A fires. The system 100 can effectivelyaddress a fire by one or more of the following: (i) extracting heat fromthe fire as the water is converted into vapor and the fuel of the fireis cooled; (ii) reducing oxygen levels by water vapor displacement ofoxygen near the fire; directly impinging wetting and cooling of thecombustibles within the data center 10; and/or (iv) enveloping theprotected area to pre-wet adjacent combustibles, cool gases and otherfuels in the area as well as block the transfer of radiant heat toadjacent combustibles.

Moreover, operation of the preferred embodiments of the system 100described herein preferably provide effective water mist fire protectionto address a fire with or during continuous or simultaneous operation ofthe ventilation system 18. Thus, the preferred water mist fireprotection system 100 does not require that the ventilation system 18 beinterlocked such that the ventilation system shuts off during operationof the fire protection system 100. Unlike prior known systemsconstructed under existing industry standards or recommendations,cooling air CA can remain circulating during operation of the fireprotection system 100. In a preferred method of addressing a fire in thedata center, the preferred fire protection system 100 addresses the firein the data center 10 by generating a water mist from a plurality ofinterconnected water mist nozzles 102 disposed either above or beneaththe raised floor 14 in response to the fire while operation of theventilation system 18 is maintained during the water mist generation.More particularly, the system 100 and its method of addressing a firepreferably provides for effective fire protection with a water mist inthe presence of the forced and more preferably continuous air flow CA,HA from the Ventilation system.

By using automatic or sealed, thermally responsive nozzles 102,preferred embodiments of the system 100 can be configured for operationas a wet pipe system, in which the piping 104 interconnecting thenozzles is filled with water up to the internal seal of the nozzle 102in an unactuated state of the system 100. Upon thermal actuation of oneor more nozzles 102, water is immediately discharged for impact againstthe nozzle diffuser 102 a to generate the water mist. However unlikepreviously known fire protection systems for data centers constructedunder the industry standards and recommendations, alternativeembodiments of the system 100 can be configured as either a dry pipe orpreaction system in which the interconnecting pipes 104 are maintaineddry in an unactuated state of the system. Thus, the system 100 caninclude a fluid control valve 106 to control the flow and delivery ofwater to the nozzles 102 upon thermal actuation of one or more nozzles102. In an alternate preferred operation of the system 100 as apreaction system, a fire detection, signal is generated in response to afire and the fluid control valve 106 is operated in response to thedetection signal to fill the network of interconnecting pipes 104 withwater before thermal actuation of one or more automatic water mistnozzles 102. Upon thermal actuation of one or more nozzles 102, water isdischarged for impact against the diffuser 102 a of the actuated nozzlesand a water mist is generated to address the fire.

Accordingly, preferred embodiments of the system 100 can further includethe fluid control valve 106 for connecting the network of pipes 104 tothe water supply FL and more particularly control the flow and pressureof fluid delivered to the nozzles. The fluid control valve 106 ispreferably electrically operated and controlled by a controller 108.Thus the controller 108 is coupled to the fluid control valve 106 andgenerates an appropriate control signal to open the valve 106 to permitthe flow of water from the supply FL out the fluid control valve 106,through the network of pipes 104 for delivery to the nozzles 102 of thesystem 100. The controller 108 preferably generates the control signalto operate the valve 106 in response to a detection signal indicating afire. To detect a fire, the system 100 preferably includes one or moredetectors 110 for detecting a fire within the data center 10 andgenerating a detection signal DS indicating a fire. The detector 110 canbe any type of sensor capable of detecting the start or presence of afire, such as for example a thermal, smoke or particulate sensor andgenerating an appropriate detection signal DS. The controller 108 isappropriately coupled to the controller 108 wired or wirelessly toreceive the detection signal DS and generate the appropriate controlsignal CS for operation of the fluid control valve 106 in a preferablysingle interlock manner. As a dry pipe or preaction system, thepreferred system 100 experiences a fluid delivery delay at full fluidpressurization from the water supply FL to the one or more actuatednozzles 102. The controller 108, its operation of the valve 106, and thenetwork of pipes preferably define a fluid delivery delay time of nomore than sixty seconds (60 sec.) and more preferably no more thanthirty seconds (30 sec.). Exemplary embodiments of the fluid controlvalve, controller, the detector and a single interlock configuration areshown and described in greater detail in Tyco Fire Products LP technicaldata sheets TFP1420 entitled “Preaction System with DV-5 Deluge ValveSingle Interlock, Supervised—Electric Actuation 1½ thru 8 inch (DN40thru DN200)” (Oct. 2014) and TFP2270, entitled “AQUAMIST Mist ControlCenter (MCC) Pump Skid Unit (Oct. 2014). Each of TFP1420 and TFP2270 isincorporated by reference in its entirety.

The nozzles 102 are located and installed to provide or define one ormore fire protection configurations of particularized regions of thedata center including: an above-the-floor configuration, abelow-the-floor configuration; and/or a local application configurationto provide localized water mist fire protection to the one or more cabletrays 17 disposed beneath the floor 14. Moreover, preferred nozzles havebeen identified for use in the preferred system 100 that effectivelyprovide for water mist fire protection for data centers without theinstallation and construction requirements and limitations under theindustry accepted recommendations and standards previously describedsuch as, for example, (i) wet only system type fire protection; (ii)ventilations system interlocking; and (iii) the use of non-propagatingcables in the cable trays. Accordingly, preferred methods and systems100 of water mist fire protection of a data center provide for locatinga plurality of automatic water mist nozzles 102 at least one of above orbelow the raised floor 14 and interconnecting the automatic water mistnozzles to a water supply for generating the water mist to address afire in the presence of a continuous flow of air from the ventilationsystem 18 for the protection of the data center includingnon-propagating and propagating cable. Additionally, the preferredsystems and methods provide for a water mist fire protection system thatcan be either a dry pipe system or a preaction system.

Referring to FIGS. 1B, 1C, 1D, schematically shown are a plurality ofpreferred nozzles 202, each having a diffuser 202 a, located below theraised floor 14 to define preferred below-the-floor configuration andlocalized application configuration in the interstitial space S for theprotection of the data center 10. The plurality of located nozzles 202are shown located to protect propagating cable or non-propagating cablein at least one below-the-floor cable tray 17. In one preferredembodiment of the below-the-floor configuration, for example as seen inFIGS. 1B and 1C, the preferred nozzles 202 are located and installedbelow the raised floor in an upright configuration. Once installed, theupright nozzles 202 and their diffusers 202 a preferably define aminimum diffuser-to-floor distance or clearance between the floor andthe diffuser preferably of no more than a maximum of 3 in. (7.6 cm.).Where a preferred upright nozzle 202 is located beneath a floor grateregion 20, the nozzle is inset preferably no further than a maximum 2in. (51 mm.) from a lateral or elongate edge of the floor grate 20. Thenozzles 202 define a preferred a nozzle-to-nozzle spacing S×S rangingfrom a minimum 6 ft.×6ft. (1.8 in×1.8 in) to a maximum 12 ft.×12 ft.(3.7 m×3.7 m), and no more than 12 ft. (3.7 m.) from an elongated edge17 a of any cable tray 17 beneath the floor regardless of whether thecable tray is spaced from one or more floor grates 20 a, 20 b, as seenin FIGS. 1B and 1C; or beneath a floor grate 20 as seen, for example, inFIG. 1D. The preferred nozzles 202 define a preferred nozzle pressure of110 to 250 psi. (7.6 to 17.2 bar). Hydraulically, the preferredbelow-the-floor nozzles 202 can be hydraulically designed to the mosthydraulically demanding area in the system 100 or alternativelyhydraulically designed to an area-of-coverage design defined by apreferred minimum six nozzles.

Additionally or alternatively, the one or more of preferably uprightnozzles 202. located below the floor 14 can provide for localizedapplication of water mist in the protection of the below-the-floor cabletray 17 and the cable housed therein as seen schematically, for example,in FIG. 1E. In particular, the group of water mist nozzles are installedin an upright configuration with a nozzle-to-nozzle spacing S×S rangingfrom a minimum 6 ft.×6 ft. (1.8 in×1.8 m) to 12 ft.×12 ft. (3.7 m×3.7 m)with each of the nozzles 202 including a diffuser 202 a at adiffuser-to-floor distance being no more than a maximum of 3 in. (7.6cm.). In the preferred localized application, the preferred nozzles 202are preferably spaced no more than 12 in. (30.5 cm.) from an elongatededge 17 a of the cable tray, and are preferably not located over top ofthe cable tray 17. The preferred localized application configuration ispreferably hydraulically configured to a minimum four nozzles per designarea. The preferred localized application configuration can provide foreffective water mist fire protection of the cable tray 17 without havingto install a complete grid for just the cable tray 17.

Shown in FIGS. 2A and 2B are elevation and cross-sectional views of apreferred automatic nozzle 202 for use in the below-the-floor andlocalized applications configurations of the preferred methods andsystems described herein. The preferred nozzle 202 generally includes aframe body 210 for coupling to a branch line of the interconnectingpiping network 104, an internal seal assembly 212, a thermallyresponsive trigger 214, and a preferred diffuser 202 a for generatingthe water mist to address a fire. The frame body 210 includes an inlet210 a, an outlet 210 b with a passageway 210 c extending between theinlet 210 a and the outlet 210 b. The nozzle 202 define a dischargecoefficient of a preferably nominal K-Factor. Preferably, the nozzle 202defines a nominal K-factor of less than 1 gpm/psi^(1/2) and is morepreferably 0.59 gpm/psi^(1/2).

The frame body 210 further preferably includes a pair of frame arms 210d diametrically opposed about the outlet 210 b. The diffuser 202 a issupported from and spaced from the outlet 210 b by the frame arms 210 d.Once coupled to a water supply pipe 104, the preferred diffuser 202 aand frame body 210 defines a preferred upright orientation. The framearms 210 d preferably converge toward an apex or knuckle 210 e axiallyaligned with the passageway and outlet 210 c, 210 b. The diffuser 202 ais preferably engaged with and centered with the knuckle 210 c. As seenin FIG. 2C, the preferred diffuser 202 a is a preferably planar memberwith a central portion 203 a axially aligned and centered with thepassageway 210 c and an outer peripheral portion 203 b circumscribedabout the central portion 203 a to define a substantially circularperiphery with a preferred diameter DIA 1 of 1.7 inches (43.2 mm). Thepreferred peripheral portion 203 b includes a plurality of spaced aparttines (203 c 1, 203 c 2, 203 c 3, . . . 203 ci) to define a plurality ofopen ended slots 203 d formed therebetween extending radially inwardpreferably at equal distance toward the central portion 203 a.

In an unactuated state of the nozzle 202, the sealing assembly 212 issupported in the outlet 210 b by the thermally responsive trigger 214which is preferably embodied as thermally responsive glass bulb 214. Theglass bulb 214 is supported against the sealing assembly 212 by theframe body 210 by a load or compression screw 215. In its thermalresponse to the fire, at a desired activation time, the bulb 214ruptures thereby releasing its support from the sealing assembly whichis preferably ejected from the outlet by an ejection spring 217. Thethermally responsive element 214 can have a temperature rating rangingbetween about 125° F. to about 365° F., preferably 135° F., 155° F.,175° F., 200° F., 286° F., or 360° F., and more preferably is any one of135° F. or 155° F. The bulb 214 is preferably configured with a ResponseTithe Index (RTI) of 50 (meters-seconds)^(1/2) or less and preferablyany one of 24 or 32 (meters-seconds)^(1/2) so as to have a fastresponse, and more preferably, the bulb 214 is such that the nozzle 202can be a quick response device.

Disposed within the inlet 210 a is a strainer 219 to filter out debriswhich may clog or damage the internal passageway of the nozzle 202.Preferably included within the passageway 210 c is an orifice insert 250preferably supported by a shelf or shoulder formed along the interiorwalls of the passageway 210 c. The orifice insert 250 includes aninterior through bore 252 through which incoming fluid flows. Theorifice insert 250 and through bore 252 define the preferred K-factor ofless than 1.00 gpm/(psi)^(1/2), preferably in the range from about 0.5to 0.70 gpm(psi)^(1/2), and more preferably is 0.59 gpm/(psi)^(1/2) (8.5lpm/bar^(1/2)). Passageways defining larger or smaller K-factors can beemployed provided the resulting water mist is effective in addressing afire in the presence of an airflow and/or can be used in the protectionof propagating cable. Upon thermal actuation of the nozzle 202, waterpasses through the orifice insert 250 and its through bore 252 fordischarge from the outlet 210 b in a preferably upward direction toimpact the diffuser 202 a for generation of the water mist to addressthe fire in a manner as described. A commercial embodiment of thepreferred nozzle 202 is shown and described in Tyco Fire Products LPtechnical data sheet TFP2201, entitled “Ultra Low Flow AQUAMIST NozzlesType ULF AM30 Automatic (Closed)” (May 2015).

Applicant has developed a preferred Method and criteria for theidentification of the nozzles for preferred use in the system 100 andits embodiments described herein. Moreover, the preferred methods can beused for identifying nozzles to use in a fire test for water mistsystems such as for example water mist test protocols and criteriaoutlined and developed by FM Approval in the planned update to StandardClass 5560. The preferred method of identifying nozzles includes adistribution analysis in a below-the-floor arrangement. Shown in FIG. 4Aand FIG. 4B are schematic views of a test set-up 510 for evaluating thewater mist patterns of nozzles for use in the system 100. The testset-up 510 includes a deck 512 and raised floor 514 spaced from the deck512 by a clearance distance of three feet (3 ft.) Mounted between thedeck and floor 512, 514 is a first cable tray 517 a, and a second cabletray 517 b. The top of the first cable tray 517 a is located at apreferred distance of twelve inches from the raised floor 514 and thetop of the second cable tray 517 b is located at a preferred distance oftwenty-four inches from the raised floor 514. Located over the firstcable tray 517 a and beneath the raised floor 514 atdiffuser-to-floor-clearance distance of four inches (4 in.) are twopreferred upright test nozzles 2021, 2022 such as previously described.Each nozzle is spaced inset from the wall 516 by a distance of sixinches (6 in.). The two nozzles 2021, 2022 are spaced apart at adistance X of four meters (4.0 m) (13.1 ft.).

Located on the deck 512 are a group of water collection pans 518 thatincluded pans disposed along the wall 516 and centered between the twopreferred nozzles 2021, 2022. The tops of the pans measure about 1ft.×1.ft. Two sets of discharge tests were conducted. In the first setof tests, water was delivered at a pressure of 110 psi. to the twonozzles 2021, 2022 having an orifice insert defining a K-factor of 0.59gpm/(psi)^(1/2) to provide for a flow of 6.2 gallons per minute (GPM).Water was discharged for a duration of 4 minutes. In the second set oftests, water was delivered at a pressure of 140 psi, to the two nozzles2021, 2022 with the orifice insert defining a larger K-factor of 0.81gpm/(psi)^(1/2) to provide for a flow of 9.6 gallons per minute (GPM).Water was discharged again for a duration of four minutes (4 min.). Eachof the collection pans 518 were appropriately weighed after thedischarge period to determine the distribution weight rate in the pan.An array of eight collection pans 518 disposed about the midline (Y--Y)between the two nozzles 2021, 2022 were evaluated. Summarized in thetables below are the average measurements of the distribution weightrates in each of the eight collection pans in units of ounces per minute(oz./min.).

K-Factor = 0.59 K-Factor = 0.81 Column Column Column Column Row −1 +1Row −1 +1 1 5.1 7.7 1 10.4 12.2 2 3.4 3.6 2 6.3 8.2 3 3.7 4.8 3 7.4 6.14 4.7 4.8 4 5.7 5.6

By looking at the variations between particular rows it was determinedthat the preferred nozzle 202 and its diffuser could provide for a watermist to effectively address a fire and protect a data center in a mannerdescribed herein. In particular, the variability in the subject array ofeight collection pans from the wall 516 to four feet (4 ft.) inset waswithin acceptable ranges. It was noted that a decrease in weight ratefrom the first row to the second row was no more than 60% and ispreferably less than about 50%. It was further noted that the changefrom the second row of collection pans to either the third or fourth panwas about 5-40% and is preferably in the range of 30-40%. Although thepreferred distribution testing is conducted without forced ventilationor continuous air flow and without a fluid delivery delay, the resultantrates of weight distribution indicates the suitability of a nozzle togenerate an effective mist for fire protection in the presence of forcedventilation or when subject to a fluid delivery delay. Accordingly,water mist distributions patterns have been identified which overcomethe limitations under the current standards and recommendations.Moreover, a method of water mist fire protection is provided thatincludes obtaining preferred automatic mist nozzles; and distributingthe nozzles for installation above or below the raised floor to addressa fire with a mist in the presence of the continuous flow of air,protect fire propagating cable or provide for one of dry pipe orpreaction fire protection. Obtaining a nozzle can include identifying anozzle for use in a preferred water mist system using a preferred waterdistribution system. Alternatively, nozzles can be obtained byprocurement or manufacture which can be identified for use in a watermist fire protection system as described. Distributing the nozzle caninclude selling, shipping or otherwise providing the obtained nozzlesfor installation in a preferred water mist fire protection system.

Shown in FIGS. 3A-3B are elevation and cross-sectional views of anotherpreferred automatic nozzle 302 identified for use in the below-the-floorconfigurations of the preferred methods and systems described herein andmore preferably for use in the local application for protection ofbelow-the-floor cable trays 17. The preferred nozzle 302 generallyincludes a frame body 310 similar to that shown in FIGS. 2A and 2B. Theframe 310 is configured for coupling to a branch line of theinterconnecting piping network 104 in a preferably pendentconfiguration, an internal seal assembly 312, a thermally responsivetrigger 314, and a preferred diffuser 400 for generating a water mist toaddress fire. The frame body 310 includes an inlet 310 a, an outlet 310b with a passageway 310 c extending between the inlet 310 a and theoutlet 310 b. The outlet 310 b and passageway 310 c define a dischargecoefficient of a preferably nominal K-factor. Preferably, the nozzle 302defines a nominal K-factor of less than 1 gpm/psi^(1/2) and is morepreferably 0.59 gpm/psi^(1/2).

The frame body 310 further preferably includes a pair of frame arms 310d diametrically opposed about the outlet 310 b. The diffuser 400 issupported from and spaced from the outlet 310 b by the frame arms 310 d.Once coupled to a fluid supply pipe 104, the preferred diffuser 400 andframe body 310 defines a preferred pendent orientation. The frame arms310 d preferably converge toward an apex or knuckle 310 e axiallyaligned with the passageway and outlet 310 c, 310 b. The diffuser 400 ispreferably engaged with and centered with the knuckle 310 e.

In an unactuated state, of the nozzle 302, the sealing assembly 312 issupported in the outlet 310 b by the thermally responsive trigger 314which is preferably embodied as a thermally responsive glass bulb 314.The glass bulb 314 is supported against the sealing assembly 312 by theframe body 310 by a load or compression screw 315. In its thermalresponse to the fire, at a desired activation time, the bulb 314ruptures thereby releasing its support from the sealing assembly 312which is preferably ejected from the outlet by an ejection spring 317.The thermally responsive element 314 can have a temperature ratingranging between about 100° F. to about 400° F., and more preferably isany one of 135° F., 155° F., 175° F., 200° F., 286° F., or 360° F. Thebulb 314 is preferably configured with a Response Time Index (RTI) of 50(meters-seconds)^(1/2) or less and preferably any one of 24 or 32(meters-seconds)^(1/2) so as to have a fast response, and morepreferably, the bulb 314 is such that the nozzle 302 can be a quickresponse device.

Disposed within the inlet 310 a is a strainer 319 to filter out debriswhich may clog or damage the internal passageway of the nozzle 302.Preferably included within the passageway 310 c is an orifice insert 350preferably supported by a shelf or shoulder formed along the interiorwalls of the passageway 310 c. The orifice insert 350 includes aninterior through bore 352 through which incoming fluid flows. Theorifice insert 350 and through bore 352 define the preferred K-factor ofless than 1.00 gpm/(psi)^(1/2), preferably in the range from about 0.5to 0.70 gpm/(psi)^(1/2), and more preferably is 0.5 gpm/(psi)^(1/2) (8.5lpm/bar^(1/2)). Upon thermal actuation of the nozzle 302, water passes-through the orifice insert 350 and its through bore 352 for dischargefrom the outlet 310 b to impact the diffuser 400 for generation of thewater mist to address the fire.

As seen in FIG. 3C, is the preferred diffuser 400 of the preferrednozzle 302. In plan, the diffuser 400 defines a substantially. circularshape with an outer peripheral edge 402 formed about a central diffuseraxis. The diffuser 400 includes a central bore 404 for mounting aboutthe frame 310. The diffuser 400 is a substantially frustoconical memberhaving an upper surface 406 and a lower surface 408 that is preferablysubstantially parallel to the upper surface 406. Preferably, thediffuser element 400 includes a substantially planar central base region406 a and an outer annular substantially planar region 406 c in whicheach of the central and outer regions of the upper surface 406 aredisposed orthogonal to the nozzle axis when the diffuser element 400 isinstalled about the frame 310. The outer planar region 406 c and itsperipheral edge 402 define the maximum outer diameter DIA2 of thediffuser 400 so as to preferably be 1.22 inches (31.0 mm). The diffuserelement 400 is further preferably formed such that the upper surface 406defines a generally annular intermediate region 406 b between thecentral region 406 a and the outer region 406 c. The intermediate region406 b preferably defines a truncated cone slanted at a downward angle a,relative to a plane parallel the central and outer planar regions 406 a,406 c. The angle a preferably ranges between about e.g. in the range ofabout 15° to about 60° and is more preferably about 18°.

The surfaces of the diffuser 400 further define a plurality of slots andthrough holes through which fluid flows to form the water mist patternof the nozzle 302. Preferred embodiments of the nozzle 302, its diffuser400 and water mist pattern are shown and described in U.S. PatentPublication No. 2011/0315406. A commercial embodiment of the preferrednozzle 302 is shown and described in Tyco Fire Products LP technicaldata sheet TFP2229, entitled “Ultra Low Flow AQUAMIST Nozzles Type ULFAM29 Automatic (Closed)” (May 2015). Each of U.S. Patent Publication No.2011/0315406 and TFP2229 is incorporated by reference in its entirety.

In the preferred diffuser element 400, the plurality of slots preferablyincludes at least three groups of slots 410, 412 and 418. Generally,each of the slots has an initial portion, a terminal portion and anintermediate portion that is continuous and disposed between the initialand terminal portions. The initial portion of the slot is defined by anopening along the peripheral edge 402 of the diffuser element 400. Theopening forms a pair of spaced apart walls in the diffuser 400 thatextend inward toward the diffuser central axis so as to define theintermediate portion of the slot. In each of the slots of the diffuserelement 400, the pair of walls converge to form the end face of the slotand define the terminal end portion of the slot. The spacing between thewalls define the width of the slot. The spacing between the walls of theslot can be constant along the length of the slot or alternatively thespacing between the walls may vary. Moreover, the wall spacing of theslot can vary either continuously along the slot length or varydiscretely such that one portion of the slot varies from another portionof the slot, for example, the terminal portion may be wider than theinitial or intermediate portion of the slot.

In the preferred embodiment of the diffuser element 400, the groups ofslots 410, 412, 418 vary with respect to one or more of the slotfeatures such as, for example, slot width, slot length, and/or geometryof any one of the initial, intermediate or terminal portions of theslot. The first group of slots 410 in which the opening and wall of theslot are dimensioned to define a preferred constant width along thelength of the slot between the initial and intermediate portions of theslot. The terminal portion of the slot defines a slot width greater thanthe slot width of the initial or intermediate portions of the slot.Within the first group of slots 410, the preferred embodiment of thediffuser element 400 includes at least three types of slots 410 a, 410b, 410 c which vary with respect to one or more of the slot featuressuch as, for example, slot width and/or geometry Of any one of theinitial, intermediate or terminal portions of the slot. For example, theslot widths the initial and intermediate portions vary from slot type toslot type.

In the second group of slots 412, the slot opening and walls arepreferably spaced to define a slot width that is substantially constantalong the slot length from the initial portion through the intermediateportion of the slot. The terminal portion and end face of the slot ispreferably defined by a radius of curvature whose center is centrallydisposed between, the two walls of the slot so as to be located alongthe central axis of the slot. The terminal portion of the slots 412 ispreferably located such that the slot length of the second group ofslots 412 is greater than the slot length of the first group of slots410.

The preferred third group of slots 418 has its opening along aperipheral edge 402 and preferably located along the end face of theterminal portion of a slot in the first group of slots 410. The wallsdefining the slot width in the third group preferably diverge away fromone another in the inward direction such that the slot width broadens atpreferably constant rate from the initial portion through theintermediate portion in the inward direction. The terminal portion andend face of the slot is preferably located more radially inward than theterminal portions of either the first group 410 or second group 412 ofslots. The formation of the diffuser 400 can bring the walls at theinitial portion of the slots of the third group of slots 418 into closecontact such that the third group of slots 418 act as through holesforming a substantially tear dropped shaped opening in the diffuserelement that is completely bound by an effectively continuous wall.

Each group of slots and through holes is preferably symmetrically andequiradially disposed over the diffuser element 400. More specifically,the first type of slots 410 a preferably include two pairs ofdiametrically opposed slots; the second type of slots 410 b of the firstgroup 410 preferably includes two pairs of diametrically opposed slotsdisposed slots; each pair disposed on a pair of orthogonal axespreferably located forty-five degrees (45°) relative to the first typeof slots 410 a. The third type of slots 410 c of the first group 410preferably includes two pairs of diametrically opposed slots; each pairdisposed respectively at an angle of about eighteen degrees (18°)relative to one of the first type of slots 410 a. The second group ofslots 412 preferably includes two pairs of diametrically opposed slotslocated at an angle of about eighteen degrees relative to the first typeof slot such that radially adjacent slots of the third type 410 c of thefirst group 410 and the slots of the second group 412 are radiallyspaced by about fifty degrees (50°). The third group of slots 418preferably includes pair of diametrically opposed slots preferablyaxially aligned with one pair of diametrically opposed slots of thefirst type 410 a of the first group 410. More preferably, the slots ofthe third group 418 are centered between slots of the third type 410 cof the first group 410.

The diffuser 400 also preferably includes a plurality of through holes.More preferably, the diffuser element 400 includes a plurality of groupsof through holes 414, 416 with a geometry that preferably varies groupto group. For example, the first group of through holes 414 ispreferably substantially elliptical in shape and the second group ofthrough holes 416 is substantially key-holed shaped. The second group ofthrough holes 416 are also preferably elongated so as to have a majoraxis and a minor axis orthogonal to the major axis. The major axispreferably intersects the central axis of the diffuser 400. The secondgroup of through holes 416 are each defined by a first radius and asecond radius each having a center disposed along the major axis of thethrough hole 416. The second radius is preferably smaller than the firstradius so that the through hole 416 is substantially key holed shape,tapering narrowly in the inward direction.

The first through holes 414 preferably includes two pairs ofdiametrically opposed through holes in which each through hole has itsminor axis aligned with the orthogonal central axes of the first type ofslots 410 a of the first group 410. The second group of through holes416 preferably include two pairs of diametrically opposed through holesin which their major axes are disposed on intersecting axes. Morepreferably, the second through holes are oriented such their major axesare disposed at a radial angle of about twenty-six degrees to thecentral axes of the first type of slots 410 d of the first group 410.

Referring back to FIG. 1F and FIG. 1G, an alternate installation isprovided for localized application of water mist in the protection ofthe below-the-floor cable tray 17 and the cable housed therein. Thepreferred plurality of nozzles 302 of FIGS. 3A-3C are installed in apendent configuration with a nozzle-to-nozzle spacing ranging from aminimum 6 ft.×6ft. (1.8 m—1.8 m) to a maximum 8 ft.—8 ft. (2.6 m×2.6 m).The preferred nozzles 302 define a preferred working nozzle pressure of11.0 to 250 psi. (7.6 to 17.2 bar). The preferred localized applicationconfiguration is preferably hydraulically configured to a minimum fournozzles per design area. The diffuser 400 is disposed at adiffuser-to-floor distance of no more than a maximum of 7.75 in. (19.7cm.) and spaced no more than 12 in. (30.6 cm.) from an elongated edge 17a of at least one below-the-floor cable tray such that the nozzle 302 ispreferably not directly above the at least one below-the-floor cabletray.

The preferred method and systems of water mist fire protectionpreferably includes water mist generation from above the floor 14. Inone particular preferred embodiment, a plurality of nozzles 302, as seenin FIGS. 3A-3C, are installed above the floor 14 and beneath the ceiling16 in a pendent configuration as schematically shown in FIG. 1A. In apreferred installation, the nozzles 302 are located and installed todefine a nozzle-to nozzle spacing ranging from a minimum 6 ft.×6ft. (1.8m×1.8 m) to 12 ft.×12 ft. (3.7 m×3.7 m), each of the pendent nozzleshaving a diffuser defining a diffuser-to-ceiling distance of 1.75 in. to4 in. (45 mm to 102 mm). With the preferred nozzles 302 define apreferred working nozzle pressure of 110 to 250 psi. (7.6 to 17.2 bar);the preferred above-the-floor configuration, the nozzles 302 arepreferably connected in a grid to define a hydraulic design demand of atleast the most remote fourteen (14) nozzles and more preferably the mostremote eighteen (18) nozzles in the system 100.

As with the below-the-floor with grating arrangements of FIGS. 1F and1G, the nozzles 302 can be used in an above-the-floor configuration withgrating for ceilings. More specifically, the nozzles 302 can be arrangedand spaced below and about a ceiling grate preferably centered in theaisle between the server cabinets with walls or barriers to provide ahot air aisle containment area between the servers. With a nozzle 302centered below the grate, protection for the containment area can berealized.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, it is intended that the present invention not be limited tothe described embodiments, but that it has the full scope defined by thelanguage of the following claims, and equivalents thereof.

1.-33. (canceled)
 34. A method of water mist fire protection,comprising: locating a plurality of automatic water mist nozzles so thatthe plurality of automatic water mist nozzles are at least one of aboveor below a raised floor of a data center, upright, having anozzle-to-nozzle spacing greater than or equal to 6 feet by 6 feet andless than or equal to 12 feet by 12 feet, and having a diffuser of eachautomatic water mist nozzle spaced less than or equal to 3 inches fromthe floor, the floor disposed above a deck of the data center at no morethan a maximum distance of 3.28 feet to define an interstitial spacetherebetween, at least one cable tray disposed between the floor and thedeck at a distance of no less than 12 inches from the floor, eachdiffuser spaced less than or equal to 12 inches from an elongated edgeof the at least one cable tray; and interconnecting the automatic watermist nozzles to a water supply to generate a water mist to address afire in the at least one above or below the raised floor in the presenceof at least one of: (i) a continuous flow of air through theinterstitial space, (ii) fire-propagating cable in the at least onecable tray, and (iii) a fluid delivery delay from the water supply tothe plurality of automatic water mist nozzles.
 35. The method of claim34, wherein locating the plurality of nozzles includes locating theplurality of nozzles below the raised floor in which each nozzleincludes a frame body having an inlet for receipt of water, an outletwith a passageway extending between the inlet and the outlet to define adischarge coefficient of a nominal K-Factor of less than 1 gpm/(psi)1/2,a seal assembly, a thermally responsive trigger to support the sealassembly in the outlet; the diffuser coupled to the frame body andspaced from the outlet, the diffuser being a planar member with acentral portion axially aligned with the passageway and an outerperipheral portion circumscribed about the central portion to define asubstantially circular periphery, the outer peripheral portion includinga plurality of spaced apart tines to define a plurality of open endedslots formed between the tines and extending radially inward at an equaldistance, the frame body including a pair of frame arms diametricallyopposed about the outlet to support the diffuser spaced from the outlet.36. The method of claim 34, wherein locating the plurality of nozzlesincludes locating the plurality of nozzles relative to at least onebelow-the-floor cable tray that includes the propagating cable.
 37. Themethod of claim 34, wherein locating the plurality of nozzles includeslocating at least one nozzle directly beneath a floor grate region ofthe raised floor, the at least one nozzle being no further inset than amaximum 2 in. (51 mm.) from a lateral edge of the floor grate region.38. The method of claim 34, wherein locating the plurality of nozzlesincludes spacing the nozzles each nozzle is not directly above the atleast one below-the-floor cable tray.
 39. The method of claim 34,wherein the plurality of nozzles is hydraulically designed with aworking pressure ranging from 110 to 250 psi. to any one of: (i) a mosthydraulically demanding area; or (ii) a design area of four to sixnozzle.
 40. The method of claim 34, wherein locating the plurality ofnozzles includes installing a group of nozzles to provide for localizedapplication and protection of at least one below-the-floor cable tray,the group of nozzles being in a pendent configuration with anozzle-to-nozzle spacing ranging from a minimum 6 ft.×6 ft. (1.8 m×1.8in) to 8 ft.×8 ft. (2.6 in×2.6 m) with a diffuser at a diffuser-to-floordistance of no more than a maximum of 7.75 in. (19.7 cm.) and spaced nomore than 12 in. (30.6 cm,) from an elongated edge of at least onebelow-the-floor cable tray such that the group of nozzles is notdirectly above the at least one below-the-floor cable tray.
 41. Themethod of claim 34, wherein locating the plurality of nozzles includesinstalling the plurality of nozzles above the floor and beneath theceiling.
 42. The method of claim 34, wherein locating the plurality ofnozzles includes locating the plurality of nozzles above the floor andbeneath the ceiling by installing the nozzles in a pendentconfiguration, each diffuser defining a diffuser-to-ceiling distance of1.75 in. to 4 in. (45 mm to 102 mm).
 43. The method of claim 34,comprising: locating at least one nozzle beneath a ceiling grate. 44.The method of claim 34, comprising: the plurality of nozzles ishydraulically designed with a working pressure ranging from 110 to 250psi. (7.6 to 17.2 bar) to any one of: (i) a design area of four nozzlesor (ii) a most hydraulically demanding area of 14-18 nozzles.
 45. Themethod of claim 34, comprising: interconnecting the automatic water mistnozzles to the water supply by interconnecting a fluid control valvebetween the water supply and the plurality of automatic nozzles.
 46. Themethod of claim 34, comprising: interconnecting the fluid control valveby providing for a dry network of pipes interconnecting the plurality ofnozzles to the fluid control valve.
 47. The method of claim 34,comprising: interconnecting the fluid control valve by providing for adry network of pipes that defines a fluid delivery delay time of no morethan 30 seconds.
 48. The method of claim 34, comprising: interconnectinga fluid control valve with a detector for detecting a fire to operatethe fluid control valve before actuation of any one of the plurality ofautomatic water mist nozzles.
 49. The method of claim 34, comprising: atleast one diffuser is a planar member with a central portion axiallyaligned with the passageway and an outer peripheral portioncircumscribed about the central portion to define a substantiallycircular periphery, the peripheral portion including a plurality ofspaced apart tines to define a plurality of open ended slots formedtherebetween extending radially inward at an equal distance, and whereinthe frame body includes a pair of frame arms diametrically opposed aboutthe outlet to support the diffuser spaced from the outlet.
 50. Themethod of claim 34, comprising: providing the continuous flow of airusing a ventilation system while addressing the fire.
 51. The method ofclaim 34, comprising: each diffuser disperses the water mist to addressthe fire.
 52. The method of claim 34, comprising: operating theplurality of nozzles as a wet pipe system.
 53. The method of claim 34,comprising: detecting the fire using one or more fire detectors.